[pica-etherpad-db] Remove unnecessary tools

pica-etherpad-db/Dockerfile

@@ -6,3 +6,11 @@ COPY config/limit_binary_log.cnf /etc/mysql/conf.d/limit_binary_log.cnf
 # the container. But mysql refuses to use config files that are world-
 # writable, so we have to change those permissions:
 RUN chmod 644 /etc/mysql/conf.d/limit_binary_log.cnf
+
+# Remove unnecessary tools
+# This removes the following packages:
+#   gnupg gnupg-l10n gnupg-utils gpg gpg-agent gpg-wks-client
+#   gpg-wks-server gpgsm libsqlite3-0 pinentry-curses
+# GPG is probably used by mysql to encrypt logs, but this isn't used in
+# our case
+RUN apt remove --autoremove libsqlite3-0